Is Working Out While Pregnant Safe?

If you lift, run, or train consistently, you probably heard mixed messaging the second you announced you were pregnant.

"Keep doing what you're doing, but don’t let your heart rate get too high.”

“Listen to your body, but don't lift more than 20 pounds.”

So let’s answer the actual question: Is working out while pregnant safe?

For most healthy pregnancies, the answer is yes.

Exercise during pregnancy is not only safe, it’s encouraged. The American College of Obstetricians and Gynecologists (ACOG) states that in the absence of medical or obstetric complications, physical activity during pregnancy is safe and beneficial.¹

But let’s unpack the myths active women hear most often.

Myth #1: Don’t Let Your Heart Rate Go Above 150 bpm

If you’ve been told to keep your heart rate under a 150 bpm while exercising during pregnancy, that advice likely came from a single study done in 2012 (Salvesen et al., 2012).²

In that study, six pregnant elite endurance athletes exercised up to about 90% of their maximum heart rate. Researchers observed temporary decreases in uterine blood flow and temporary fetal heart rate changes at very high intensities.

But here's the problem with using this study to make blanket statements:

• There were only six participants

• No control group

• Participants were elite athletes

• No long-term fetal outcomes were measured

• The changes observed were temporary

That’s not strong enough evidence to justify a universal heart rate cap for all pregnant women. It's additionally become outdated based on new evidence.

More recently, a 2023 study by Wowdzia et al. looked at pregnant participants performing vigorous exercise while monitoring fetal heart rate and blood flow in real time.³ In healthy pregnancies, they did not find clinically meaningful harmful effects when intensity was appropriately managed.

In other words, high-intensity exercise during pregnancy did not automatically compromise fetal well-being.

This aligns with ACOG’s current guidance, which no longer recommends strict heart rate limits and instead emphasizes perceived exertion and individualization.¹

Myth #2: Exercise Can Cause Miscarriage

This is one of the most fear-inducing myths around exercise during pregnancy.

But a relatively recent study found that women who exercised during pregnancy had no increased risk of miscarriage compared to those who did not exercise (Barakat et al., 2023)⁴.

Most early miscarriages are related to chromosomal abnormalities — not whether someone continued lifting weights while pregnant.

For healthy pregnancies without contraindications, exercise does not increase miscarriage risk. However, there are certain conditions where moderate-to-vigorous exercise should be restricted or modified (Meah et al., 2020)⁵.

Think of these as red flags and yellow flags:

Red flags (absolute contraindications — stop moderate-to-vigorous exercise)

• Severe respiratory or cardiovascular disorders with exercise intolerance

• Uncontrolled or severe arrhythmias

• Placental abruption

• Vasa previa

• Uncontrolled type 1 diabetes

• Intrauterine growth restriction

• Active preterm labor

• Severe preeclampsia

• Cervical insufficiency

Yellow flags (relative contraindications — modify and coordinate care)

• Mild cardiovascular or respiratory disorders

• Mild preeclampsia

• Well-controlled type 1 diabetes

• Preterm premature rupture of membranes

• Placenta previa after 28 weeks

• Untreated thyroid disease

• Multiple nutrient deficiencies and/or chronic undernutrition

• Symptomatic, severe eating disorders

• Heavy smoking in the presence of comorbidities

Myth #3: You Shouldn’t Lift More Than 20 Pounds

The idea that lifting weights while pregnant should be capped at 20 pounds ignores training history, load tolerance, and real life. Because if that were true, most pregnant moms would be banned from picking up their toddlers.

Another relatively recent study examined heavy resistance training during pregnancy and found no increased risk of adverse fetal outcomes or miscarriage (Prevett et al., 2023)⁶. It also found lower rates of certain pregnancy complications among trained individuals (Prevett et al., 2023)⁶.

Load is also relative. What seems "heavy" to someone who's been weight training for years will be very different to someone who's never done weight training before.

So instead of limiting everyone to lifting less than 20 pounds, a more practical approach is to monitor how movements feel and watch for symptoms that signal the need to modify.

Some yellow flags to look for that signal it's time to reduce load or change exercises are:

• Pelvic heaviness or pressure

• Persistent pain during or after lifting

• Loss of control or stability during the movement

• Excessive fatigue that doesn’t resolve

Just like with cardiovascular training, the goal isn’t to follow an arbitrary number. It’s to adjust intensity based on how your body responds.

What This Looked Like During My Own Pregnancy

Research is helpful, but it can still feel abstract. So here’s what exercise during pregnancy looked like for me personally.

Overhead squats in my third trimester!

For strength training, I was able to continue lifting weights for most of my pregnancy. Instead of using percentages or specific weight targets, I trained almost entirely by feel. I paid attention to things like RPE (rate of perceived exertion), how stable I felt, and whether anything created unusual pressure or discomfort in my core and pelvic floor.

I only started scaling more towards the end of my pregnancy, because that's when my belly became too uncomfortable and started getting in the way of certain movements. Another thing I paid close attention to was pelvic pressure. If an exercise started to feel heavy in my pelvic floor, I treated that as a signal to modify the movement or reduce intensity.

Interestingly, I was able to continue Olympic lifting well into my second trimester, which was longer than I expected. Eventually the bar path started running into my belly, so I switched to dumbbells or other variations that allowed more space.

Cardio was a different story.

I have beta thalassemia minor, which means my red blood cells are smaller and have less hemoglobin, so they carry oxygen less efficiently. Normally, my body adapts to that and I don’t notice symptoms day to day. But pregnancy obviously added extra demand to my cardiovascular system, and I started getting winded with cardio much earlier than expected.

Because of that, I had to scale cardio workouts fairly early in my pregnancy. I could still run short intervals like 400 meters at a time, but longer distances — anything over about a mile — became difficult pretty quickly. Echo bike workouts were also worse than normal.

Also, remember that each pregnancy is highly individual. Another woman at my gym was pregnant around the same time as me and continued exercising almost until the day she delivered. I ended up stopping about two weeks before giving birth because I was just so uncomfortable.

Training decisions often come down to a combination of symptoms, comfort, and personal risk tolerance.

What Actually Matters When Exercising During Pregnancy

If you’re wondering whether exercise during pregnancy is safe, keep the following in mind:

RPE over percentages. As annoying as the phrase "listen to you body" is, it's exactly what you should do during pregnancy. Go by feel, meaning if the intent of the workout is to use a moderate weight, find a weight for the day that feels moderate.

Presence of symptoms. Pay attention to any symptoms you feel while exercising and adjust accordingly.

Red flags (stop exercising and consult with your OB):

• Vaginal bleeding

• Persistent dizziness

• Severe abdominal pain

• Excess vaginal fluid leakage

• Chest pain

• Regular painful contractions

  
  

Yellow flags (modify exercise, consider consulting your OB)

• Pelvic heaviness or pressure

• Persistent pain during or after lifting

• Loss of control or stability during the movement

• Excessive fatigue that doesn’t resolve

Individual physiology. Try not to compare yourself with others who are pregnant at the same time as you, even if it seems like you have the same fitness level. Everyone will respond to pregnancy differently and will have different circumstances surrounding their pregnancy.

Risk tolerance. Risk tolerance also plays a role in exercise decisions during pregnancy. Some people feel comfortable continuing higher-skill or higher-impact movements, while others prefer to scale earlier. Neither approach is right or wrong and will depend on individual comfort, experience, and personal preference.

So… Is Working Out While Pregnant Safe?

For most healthy, uncomplicated pregnancies: yes.

Exercise during pregnancy is supported by current research and ACOG guidelines, especially when taking an individualized approach. In most cases, the benefits of exercise far outweigh any risks.

So when thinking about exercise during pregnancy, it's a lot more helpful to ask "does this feel ok to me right now?" rather than "is this exercise safe during pregnancy?"

Being pregnant doesn't mean you need to start avoiding certain exercises. It's just another thing to take into consideration while training so you can adapt as your body changes.

Support for Training Through Pregnancy and Returning Postpartum

If you're navigating exercise during pregnancy or planning your return to training postpartum, working with a fitness-forward pelvic health physical therapist, such as myself, can help you stay active with confidence. If you'd like to work with me, schedule a consultation below:

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This article is for general education only and is not medical advice. If you have specific concerns, speak with your OB provider.

References

1. Physical activity and exercise during pregnancy and the postpartum period. ACOG Committee Opinion No. 804. American College of Obstetricians and Gynecologists. Obstet Gynecol 2020;135:e178–88.

2. Salvesen, K. Å., Hem, E., & Sundgot-Borgen, J. (2012). Fetal wellbeing may be compromised during strenuous exercise among pregnant elite athletes. British journal of sports medicine, 46(4), 279–283. https://doi.org/10.1136/bjsm.2010.080259

3. Wowdzia, J. B., Hazell, T. J., Berg, E. R. V., Labrecque, L., Brassard, P., & Davenport, M. H. (2023). Maternal and Fetal Cardiovascular Responses to Acute High-Intensity Interval and Moderate-Intensity Continuous Training Exercise During Pregnancy: A Randomized Crossover Trial. Sports medicine (Auckland, N.Z.), 53(9), 1819–1833. https://doi.org/10.1007/s40279-023-01858-5

4. Barakat, R., Zhang, D., Silva-José, C., Sánchez-Polán, M., Franco, E., & Mottola, M. F. (2023). The Influence of Physical Activity during Pregnancy on Miscarriage-Systematic Review and Meta-Analysis. Journal of clinical medicine, 12(16), 5393. https://doi.org/10.3390/jcm12165393

5. Meah, V. L., Davies, G. A., & Davenport, M. H. (2020). Why can't I exercise during pregnancy? Time to revisit medical 'absolute' and 'relative' contraindications: systematic review of evidence of harm and a call to action. British journal of sports medicine, 54(23), 1395–1404. https://doi.org/10.1136/bjsports-2020-102042

6. Prevett, C., Kimber, M. L., Forner, L., de Vivo, M., & Davenport, M. H. (2023). Impact of heavy resistance training on pregnancy and postpartum health outcomes. International urogynecology journal, 34(2), 405–411. https://doi.org/10.1007/s00192-022-05393-1